说明：  OPNET仿真多种mac协议，里面包含各个协议的进程代码，可直接作为mac模块仿真。 aloha协议 aloha_ack协议 maca协议 macaw协议 fama_ack协议
(OPNET simulation of a variety of mac protocols, which contains the process code of each agreement, as the mac module can be directly simulated. aloha protocol aloha_ack protocol fama_ack protocol maca protocol macaw protocol)